JPH10301101A - Color filter substrate, manufacture thereof and liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand the visual angle characteristic of a liquid crystal panel without necessitating a new manufacturing process and making a manufacturing process complicated by forming the surface of the area of a display picture element which is the minimum unit of display surrounded by black matrices to be recessed or projecting. SOLUTION: The surface of a display picture element area 1 that is the minimum unit of the display surrounded by a black matrix layer 3 is formed so as not to be flat but recessed. Namely, the surface of a color filter layer 2(2a-2c) is formed to be recessed and also an overcoat layer is formed on the color filter layer 2 so as to maintain a surface shape. Thus, the surface of the color filter layer 2 and the surface of the overcoat layer are formed to be recessed, so that the layer thickness of a liquid crystal layer is continuously changed within the display picture element area. In the case that voltage is applied to a liquid crystal panel, the tilt angle of a liquid crystal molecule is distributed in a state where it has variation within a fixed range, so that the difference of an optical characteristic by an observing direction is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter substrate, a method for manufacturing a color filter substrate, and a liquid crystal panel.

[0002]

2. Description of the Related Art FIGS. 12A and 12B schematically show a conventional color filter substrate, and FIG.
3 to 17.

In a conventional color filter substrate, FIG.
(A), the surface of the display pixel area 1 is formed smooth, and the color filter layers 2 (2a, 2b, 2c are respectively formed of a red color filter layer and a green color When the smoothness is insufficient (see FIG. 12 (b)) as in the case of forming a filter layer and a blue color filter layer (see FIG. Further, the overcoat layer 4 is formed so that the smoothness of the display pixel region 1 is uniform. In addition, (a) of FIG.
In (b), 5 is a glass substrate. Further, in the drawing, the display pixel region 1 shows a corresponding portion of the blue color filter layer 2c for easy understanding.

The reason why the surface of the display pixel region 1 is formed smoothly is that, as shown in FIG. 13, when the liquid crystal panel is assembled, the thickness of the liquid crystal layer 7 is kept uniform. As a result, the optical characteristics in the front direction of the liquid crystal panel can be maintained satisfactorily. As shown in FIG. 14, if there is a sharp surface step in the display pixel area 1, the alignment X of the liquid crystal molecules 7a is disturbed. However, if the surface of the display pixel area 1 is formed to be smooth, it is possible to prevent such disturbance X in the alignment direction of the liquid crystal molecules 7a. Further, when the liquid crystal panel is driven by applying a voltage, the display pixel area 1 This is based on the fact that the orientation of the liquid crystal molecules 7a in the inside becomes uniform. For simplicity, in these figures, only the liquid crystal molecules 7a in the display pixel region 1 to which the voltage is applied are shown near the center. 13 and 14, reference numeral 8 denotes a transparent electrode formed on the color filter layer 2, 9 denotes an alignment film formed on the transparent electrode 8, and 12 denotes a transparent electrode.
Is a TFT array substrate, and this TFT array substrate 12
It has a separate transparent electrode 10, alignment film 11 and glass substrate 13.

[0005] Most liquid crystal panels mass-produced today operate a liquid crystal layer 7 by applying a voltage to control the orientation state of the liquid crystal layer 7 and control the polarization state of light passing through the liquid crystal layer 7. Thus, a desired display is obtained.

[0006]

However, according to the conventional color filter substrate and the liquid crystal panel,
Light passing through the liquid crystal layer 7 has different optical characteristics depending on the direction in which the liquid crystal panel is observed, because the light passing through the liquid crystal layer 7 and the angle formed with the liquid crystal molecules 7a are different depending on the incident angle and the output angle. . The viewing angle dependence of the optical characteristics is one of the major problems in the characteristics of the liquid crystal panel.

Various methods have been proposed in recent years to solve this problem. As a first method, as shown in FIG. 15, there is a method of attaching a birefringent film 14 for compensating for viewing angle dependence to the surface of a liquid crystal panel. As the birefringent film 14, a film in which the molecular arrangement is controlled in a three-dimensional direction in a plane, a film having a disk-like birefringence anisotropy, and the like have been proposed. There is a problem that the refraction film 14 is expensive and requires a new manufacturing process of attaching the film.

As a second method, as shown in FIGS. 16, 17, and 14, the display pixel 1 is divided into several regions, and the liquid crystal alignment is performed for each of the divided display pixel regions 1a and 1b. A method has been proposed in which the viewing angle is expanded by changing the state. As shown in FIG. 16, a method of changing the rubbing direction to control the orientation of the liquid crystal molecules 7a in the panel surface direction by using the divided display pixel regions 1a and 1b (9a and 11a in FIG. The alignment films 9b and 11b are the alignment films subjected to the second rubbing.) As shown in FIG. 17, the alignment films 9c and 9 differ depending on the divided display pixel regions 1c and 1d.
A method of controlling the tilt angle of the liquid crystal molecules 7a by using the materials d, 11c and 11d. Further, as shown in FIG. 14, a part of the display pixel region 1 between the transparent electrode 8 and the alignment film 9 There is a method of controlling the electric field applied to the liquid crystal layer 7 by forming a dielectric film 15 on the substrate. 13 to 17 show a state in which a voltage is applied to the display pixel region 1 corresponding to the red color filter layer 2a.

All of these methods have been effective, but they have the problem of complicating the manufacturing process, causing a reduction in the manufacturing yield, and causing the liquid crystal molecules near the boundaries of the divided regions. There has been a problem that a disturbance X (see FIG. 14) occurs in the alignment direction of 7a.

The present invention solves the above-mentioned problems, and a color filter substrate and a color filter capable of expanding the viewing angle characteristics of a liquid crystal panel without requiring a new manufacturing process or complicating the manufacturing process. It is an object to provide a method for manufacturing a substrate and a liquid crystal panel.

[0011]

In order to solve the above-mentioned problems, a color filter substrate according to the present invention is arranged such that the surface of a display pixel area which is a minimum unit of display surrounded by a black matrix is not flat, but has a concave or convex shape. It is formed in a mold.

According to the present invention, the viewing angle characteristics of the liquid crystal panel can be expanded without requiring a new manufacturing process or complicating the manufacturing process.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the color filter substrate according to the first aspect of the present invention, the surface of a display pixel region, which is the minimum unit of display surrounded by a black matrix, is formed not in a plane but in a concave or convex shape. According to this, when a liquid crystal layer is formed on a color filter substrate, the layer thickness of the liquid crystal layer continuously changes inside the display pixel region, and thus the liquid crystal panel having such a configuration is formed. When the voltage is applied to the liquid crystal layer, even if the voltage applied between the upper and lower transparent electrodes is constant in the display pixel area where the voltage is applied, the electric field applied to the liquid crystal molecules is different in the area where the liquid crystal layer thickness is different. In addition, the tilt angle of the liquid crystal molecules is distributed within a certain range, and the difference in optical characteristics depending on the viewing direction is reduced.

Further, in this color filter substrate, the difference in height between the central portion and the peripheral portion of the display pixel area is equal to 0.
It is preferable that the thickness be 2 μm or more. In the method for manufacturing a color filter substrate according to claim 3 of the present invention, after forming a black matrix layer on a glass substrate to a thickness of 1.5 μm or more, the color filter layer is formed such that a part thereof overlaps the black matrix layer. The color filter layer is formed so as to have a difference in height between a portion overlapping the black matrix layer and a portion not overlapping the black matrix layer on the surface of the color filter layer.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a color filter substrate, comprising: forming a black matrix layer on a glass substrate to a thickness of 1.5 μm or more; The overcoat layer is formed so as to cover the black matrix layer and the color filter layer, and the color filter layer on the surface of the overcoat layer where the color filter layer overlaps the black matrix layer and the color filter layer are formed. This is a difference in height from a portion not overlapping the black matrix layer.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a color filter substrate, comprising coating a photosensitive transparent resin film on the surface of a glass substrate having a black matrix formed thereon, and forming the photosensitive transparent resin film on the central portion of the pixel by photolithography. After forming the transparent resin layer, a color filter layer is formed, and a height difference between a portion corresponding to the portion where the transparent resin layer is formed and a portion corresponding to the portion where the transparent resin layer is not formed on the surface of the color filter layer is generated. It is made to let.

According to a sixth aspect of the present invention, there is provided a color filter substrate manufacturing method, wherein a photosensitive transparent resin film is applied to a surface of a glass substrate having a black matrix formed thereon, and the central portion of the pixel is formed by photolithography. After forming the transparent resin layer, a color filter layer is formed, and further, an overcoat layer is formed so as to cover the black matrix layer and the color filter layer, and corresponds to a portion where the transparent resin layer is formed on the surface of the overcoat layer. The height difference between the location and the location corresponding to the non-formed portion of the transparent resin layer is caused.

According to these manufacturing methods, a color filter substrate in which the surface of the display pixel region, which is the minimum unit of display surrounded by the black matrix, is formed not in a plane but in a concave or convex shape is favorably manufactured. can do.

Further, by forming an overcoat layer so as to cover the black matrix layer and the color filter layer, a surface step near a boundary between a region where the color filter layer overlaps the black matrix layer and a region where the color filter layer does not overlap is eliminated. As a result, the surface shape can be continuously changed, and alignment disorder due to a surface step can be prevented.

In the method for manufacturing a color filter substrate according to the fifth and sixth aspects of the present invention, the area of the transparent resin layer formed at the center of the pixel is one third of the area of the display pixel surrounded by the black matrix. Less than 0.2μ
m or more is preferable.

The liquid crystal panel according to claim 8 of the present invention is a liquid crystal panel assembled using a color filter substrate, and the color filter substrate is a minimum display unit surrounded by a black matrix. The surface of the display pixel region is formed not in a plane but in a concave or convex shape.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The components having the same functions as those in the related art are denoted by the same reference numerals, and the description thereof is partially omitted. Also,
In each drawing, a TFT element on a TFT array substrate,
Wiring and the like are omitted and simplified.

As shown in FIGS. 1 and 2, in this color filter substrate, the surface of the display pixel region 1 which is the minimum unit of display surrounded by the black matrix layer 3 is formed not in a plane but in a concave shape. I have. That is, as shown in FIG. 1, the color filter layer 2 (2a, 2b, 2
The surface of the color filter layer 2 (2a, 2b, 2c) may be formed in a concave shape as shown in FIG.
Overcoat layer 4 on color filter layer 2
Is formed.

The liquid crystal panel employing the color filter substrate is provided on the overcoat layer 4 of the color filter substrate as shown in FIGS.
A transparent electrode 8 and an alignment film 9 are provided, and a liquid crystal layer 7 is provided between a transparent electrode 10 and a TFT array substrate 12 having an additional alignment film 11.
3 and 4 show a state in which a voltage is applied to the display pixel region 1 corresponding to the red color filter layer 2a.

The color filter substrate and the liquid crystal panel are manufactured as follows. (A) of FIG.
As shown in (b), an acrylic photosensitive black resist 21 is applied to a clean glass substrate 1 with a spin coater to be thicker than usual, and prebaked at 80 ° C. for 30 minutes. Next, as shown in FIG. 5C, 1 / cm 2 is applied through a mask 22 having a desired pattern.
After exposure with an energy of 00 mW, development in an alkaline developer and heat treatment at 200 ° C. for 2 hours were performed to form a black matrix layer 3 having a desired pattern on the glass substrate 1. Then, a substrate with the substrate is obtained (see FIG. 5D).

At this time, two types of the black matrix layer 3 having a thickness of 1.5 μm and a thickness of 2.0 μm were prepared. In each case, the pattern pitch of the black matrix layer 3 was 110 μm and the width was 30 μm.

On the substrate with the black matrix,
Red, green, and blue color filter layers 2a, 2b, and 2c were formed using the same photolithography method as when the black matrix layer 3 was formed (see FIG. 5E). The pattern width of this color filter layer 2 is 110
.mu.m, and 15 .mu.m at both ends were formed so as to overlap the black matrix film 3. FIG.

Next, as shown in FIG. 5 (f), an epoxy resin-based overcoat film 4 is applied to a thickness of 2 μm using a spin coater, and heated at 200 ° C. for 2 hours to form a color filter substrate. I got

After the transparent electrode 8 is formed on the color filter substrate by sputtering and the alignment film 9 is provided, the TFT array substrate 12 is bonded, and a liquid crystal material is injected to form the liquid crystal layer 7. T shown in FIG.
An FT liquid crystal panel A (A-1, A-2) was prepared. Here, the TFT liquid crystal panel A-1 has a thickness of the black matrix layer 3 of 1.5 μm, and the TFT liquid crystal panel A-2 has a thickness of the black matrix layer 3 of 2.0 μm. The difference in thickness is not shown.

As described above, by forming the surface of the color filter layer 2 and the surface of the overcoat layer 4 in a concave shape, the layer thickness of the liquid crystal layer 7 changes continuously in the display pixel region. When a voltage is applied to the liquid crystal panel, even if the voltage applied between the upper and lower transparent electrodes 8 is constant in the display pixel region 1 to which the voltage is applied, the thickness of the liquid crystal layer 7 is different. As a result, the tilt angle of the liquid crystal molecules 7a is distributed in a certain range within a certain range, and the difference in optical characteristics depending on the viewing direction is reduced.

Further, by forming the overcoat layer 4 so as to cover the black matrix layer 3 and the color filter layer 2, the vicinity of the boundary between the region where the color filter layer 2 overlaps the black matrix layer 3 and the region where the color filter layer 2 does not overlap is formed. Of the surface can be eliminated, the surface shape can be continuously changed, and alignment disorder due to the surface step can be prevented.

Further, another embodiment of the present invention will be described with reference to FIGS. The components having the same functions as those of the above-described embodiment are denoted by the same reference numerals. As shown in FIGS. 6 and 7, in this color filter substrate, the surface of the display pixel region 1, which is the minimum unit of display surrounded by the black matrix layer 3, is formed not in a plane but in a convex shape.

That is, as shown in FIG. 6, a transparent resin film 31 is formed at the center of the display pixel region 1 on the glass substrate 1, and the color filter layer 2 is formed so as to overlap the transparent resin film 31. , Color filter layer 2
The surface of (2a, 2b, 2c) is formed in a convex shape.
Further, as shown in FIG. 7, the surface of the color filter layer 2 (2a, 2b, 2c) is similarly formed in a convex shape, and the surface of the color filter layer 2 is further formed so as to maintain this surface shape. The overcoat layer 4 may be formed.

A liquid crystal panel employing the color filter substrate is provided on the overcoat layer 4 of the color filter substrate as shown in FIGS.
A transparent electrode 8 and an alignment film 9 are provided, and a liquid crystal layer 7 is provided between a transparent electrode 10, an alignment film 11, and a TFT array substrate 12 having a glass substrate 13.

The color filter substrate and the liquid crystal panel are manufactured as follows. (A) of FIG.
As shown in (b), a photosensitive transparent resin film 31 is applied to the glass substrate 5 on which the black matrix layer 3 made of chromium is already formed by patterning using a spin coater.
Pre-bake at 30 ° C for 30 minutes. Next, as shown in FIG. 10C, exposure is performed at an energy of 30 mw per square centimeter through a mask 22 having a desired pattern, followed by development in an alkaline developing solution and 200 ° C. A heat treatment was performed for 2 hours to form a pattern of the transparent resin film 31 (see FIG. 10D).

At this time, the transparent resin film 31 has a thickness of 1.
Two types, 3 μm and 1.8 μm, were prepared. At this time, the pattern of the transparent resin film 31 was formed at the center of the display pixel region 1 so that its area was 1/3 or less of the display pixel region 1, as shown in FIG.

Next, in the same manner as when forming the color filter substrates of the liquid crystal panels A-1 and A-2 in the above embodiment, the red, green and blue color filter layers 2a, 2b and 2c were formed (see FIG. 10E). In this case, since the chromium black matrix layer 3 is used, the color filter layer 2
It is not necessary to pay particular attention to the degree of overlap between the two ends of the black matrix layer 3 and the black matrix layer 3. When the resin black matrix layer 3 is used, it is necessary to adjust the overlap between the both ends of the color filter layer 2 and the black matrix layer 3 according to the film thickness, but it is essentially required. The object of the present invention is achievable.

Next, an epoxy resin-based overcoat film 4 is applied to a thickness of 2 μm using a spin coater,
The color filter substrate was obtained by performing a heat treatment at 2 ° C. for 2 hours (see FIG. 10F).

After the transparent electrode 8 is formed on the color filter substrate by the sputtering method and the alignment film 9 is provided, the TFT array substrate 12 is bonded, and the liquid crystal material is injected to form the liquid crystal layer 7. T shown in FIG.
An FT liquid crystal panel B (B-1, B-2) was prepared. Here, the TFT liquid crystal panel B-1 is a transparent resin film 31.
Is 1.3 μm, and in the TFT liquid crystal panel B-2, the thickness of the transparent resin film 31 is 1.8 μm, and the difference in thickness is not shown.

As described above, by forming the surface of the color filter layer 2 and the surface of the overcoat layer 4 in a convex shape, the layer thickness of the liquid crystal layer 7 continuously changes in the display pixel region. Therefore, when a voltage is applied to the liquid crystal panel, even if the voltage applied between the upper and lower transparent electrodes 8 in the display pixel region 1 to which the voltage is applied is constant, the thickness of the liquid crystal layer 7 is different, so that the liquid crystal molecules 7a As a result, the tilt angle of the liquid crystal molecules 7a is distributed with variation within a certain range, and the difference in optical characteristics depending on the observation direction is reduced.

Further, by forming the overcoat layer 4 so as to cover the black matrix layer 3 and the color filter layer 2, the overcoat layer 4 is formed near the boundary between the region where the color filter layer 2 overlaps the black matrix layer 3 and the region where the color filter layer 2 does not overlap. Of the surface can be eliminated, the surface shape can be continuously changed, and alignment disorder due to the surface step can be prevented.

In these embodiments of the present invention,
When the liquid crystal panels A and B are formed, the color filter layer 2 is formed by using a photolithography method. However, the color filter layer 2 can be similarly formed by using a printing method and other methods.

The liquid crystal panel A-1 prepared by the above method,
The viewing angle characteristics of the liquid crystal panel C using A-2, B-1, B-2, and a conventional technique simultaneously prepared as a reference example were measured. The data is shown in Table 1. The comparison of the viewing angle characteristics was performed by comparing the front contrast and the elevation angles of the upper, lower, left, and right sides where the contrast becomes 10 or more or the contrast is reversed.

[0044]

[Table 1]

As shown in Table 1, in the liquid crystal panel having the structure of the present invention, the viewing angle characteristics from any of up, down, left, and right directions can be improved. At this time, although the contrast ratio from the front direction slightly decreases, it is within a range in which there is no practical problem.

The improvement of the viewing angle characteristic is more effective as the step on the surface of the display pixel area 9 is larger.
On the contrary, it turned out that the contrast in the front direction had to be sacrificed. When the height difference between the central portion and the peripheral portion of the display pixel region 1 was smaller than 0.2 μm, the viewing angle characteristics were not significantly improved.

Further, no significant difference was observed in optical characteristics between the display pixel region 1 having a concave surface (A type) and a convex surface (B type). However, according to the method for manufacturing a color filter substrate of the present invention shown in FIGS. 5 and 10, the convex type needs to add a new step of forming a pattern of the transparent resin film 31. It is advantageous without any change in the manufacturing method and the number of steps. Further, in order to reduce the number of steps in the convex type, it is necessary to form a color filter layer 2 by a printing method and adjust the viscosity of the ink used at that time.

In the case of the embodiment of the present invention, the TFT
Although the description has been made with reference to the liquid crystal panel, a TN mode liquid crystal panel is essentially the same, and a sufficient effect can be obtained.

[0049]

As described above, when the color filter substrate of the present invention is used, a liquid crystal panel having a wide viewing angle characteristic and a high display quality can be obtained by forming the surface of the display pixel region into a concave or convex shape. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a color filter substrate according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a color filter substrate according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a liquid crystal panel using the color filter substrate according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a liquid crystal panel using a color filter substrate according to a second embodiment of the present invention.

FIGS. 5A to 5F are cross-sectional views illustrating manufacturing steps for manufacturing a color filter substrate according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a color filter substrate according to a third embodiment of the present invention.

FIG. 7 is a sectional view of a color filter substrate according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of a liquid crystal panel using a color filter substrate according to a third embodiment of the present invention.

FIG. 9 is a sectional view of a liquid crystal panel using a color filter substrate according to a fourth embodiment of the present invention.

FIGS. 10A to 10F are cross-sectional views illustrating manufacturing steps for manufacturing a color filter substrate according to a fourth embodiment of the present invention.

FIG. 11 is a plan view of a color filter substrate according to a fourth embodiment of the present invention.

FIGS. 12A and 12B are cross-sectional views of a conventional color filter substrate.

FIG. 13 is a sectional view of a conventional liquid crystal panel.

FIG. 14 is a sectional view of a conventional liquid crystal panel.

FIG. 15 is a cross-sectional view of a conventional liquid crystal panel.

FIG. 16 is a sectional view of a conventional liquid crystal panel.

FIG. 17 is a sectional view of a conventional liquid crystal panel.

[Explanation of symbols]

 Reference Signs List 1 display pixel region 2 color filter layer 3 black matrix layer 4 overcoat layer 5 glass substrate 7 liquid crystal layer 7a liquid crystal molecules A-1, A-2, B-1, B-2 liquid crystal panel

Claims (8)

[Claims] The surface of a display pixel area, which is a minimum unit of display surrounded by a black matrix, is not flat,
A color filter substrate formed in a concave or convex shape. 2. The color filter substrate according to claim 1, wherein the height difference between the surface and the central portion of the display pixel region is 0.2 μm or more. 3. A black matrix layer having a thickness of 1.5 μm or more formed on a glass substrate, and a color filter layer is formed so as to partially overlap the black matrix layer, thereby forming a black matrix layer on the surface of the color filter layer. A method for producing a color filter substrate, wherein a difference in height is generated between a portion overlapping a layer and a portion not overlapping a black matrix layer. 4. After forming a black matrix layer having a thickness of 1.5 μm or more on a glass substrate, a color filter layer is formed so as to partially overlap the black matrix layer, and a black matrix layer and a color filter layer are further formed. An overcoat layer is formed so as to cover the surface of the overcoat layer, and a level difference is generated between a portion where the color filter layer overlaps the black matrix layer and a portion where the color filter layer does not overlap the black matrix layer. A method for manufacturing a color filter substrate. 5. A photosensitive transparent resin film is applied to the surface of a glass substrate on which a black matrix is formed, and a transparent resin layer is formed at a pixel central portion using a photolithography method.
Manufacturing of a color filter substrate by forming a color filter layer and causing a height difference between a portion corresponding to the portion where the transparent resin layer is formed and a portion corresponding to the portion where the transparent resin layer is not formed on the surface of the color filter layer Method. 6. A photosensitive transparent resin film is applied to the surface of a glass substrate on which a black matrix is formed, and a transparent resin layer is formed at a pixel central portion using a photolithography method.
A color filter layer is formed, and an overcoat layer is further formed so as to cover the black matrix layer and the color filter layer, and a portion corresponding to a portion where the transparent resin layer is to be formed on the surface of the overcoat layer and no formation of the transparent resin layer A method for producing a color filter substrate, wherein a difference in height from a portion corresponding to a part is generated. 7. The pixel according to claim 5, wherein the area of the transparent resin layer formed in the center of the pixel is not more than one third of the area of the display pixel surrounded by the black matrix, and the layer thickness is not less than 0.2 μm. A method for producing the color filter substrate according to the above. 8. A liquid crystal panel assembled using a color filter substrate, wherein the color filter substrate comprises:
A liquid crystal panel in which the surface of a display pixel region, which is the minimum unit of display surrounded by a black matrix, is formed not in a plane but in a concave or convex shape.